Historian Craig Shirley has accused liberal author Rick Perlstein of plagiarism in Perlstein’s new Ronald Reagan biography, The Invisible Bridge: The Fall of Nixon and the Rise of Reagan, which was published through Simon and Schuster.According to Shirley, there are nearly 50 different instances in which lines from his book, Reagan’s Revolution, appeared nearly word for word without attribution in Perlstein’s new book.

Reagan’s Revolution covers the 1976 presidential election, specifically Ronald Reagan’s primary challenge against the Republican president at that time, Gerald Ford. Perlstein’s book follows a very similar story arc and in the acknowledgments admits that Shirley saved him “3.75 months of work.”

Perlstein’s book contains no bibliography, footnotes, or endnotes, however, his sources can be found online at his own personal website rickperlstein.net.

In an exclusive with Breitbart News, Craig Shirley attacked the use of the online citations and the instances in which he claims where there was no citation at all.

Shirley wrote:

When I looked to see if Mr. Perlstein credited his many uses of Reagan’s Revolution, I found that the body of The Invisible Bridge does not credit Reagan’s Revolution at any point, and there are no footnotes, end notes, bibliography or other common form of citation in his book. Instead, buried on page 810, Mr. Perlstein directs readers to access his personal website where, after several clicks, they can uncover “A Note on Sources” for The Invisible Bridge. There, Mr. Perlstein credits some–but not all–of his uses of Reagan’s Revolution.

Shirley’s lawyer, Chris Ashby, claimed in a letter to Simon and Schuster that the the instances of alleged plagiarism were “far worse” that what they conceived in an initial review.

Ashby wrote, “Indeed, we have focused on the source notes posted on Mr. Perlstein’s website, and determined that even in those instances in which Mr. Perlstein references Reagan’s Revolution as the source of the material at issue, those references are insufficient to absolve his theft of Mr. Shirley’s original expression and ideas.”

Shirley gave Breitbart News some examples of the alleged plagiarism:

Reagan’s Revolution (2005)

Page 297: “Even its ‘red light’ district was festooned with red, white, and blue bunting, as dancing elephants were placed in the windows of several smut peddlers.”

The Invisible Bridge (2014)

Page 771: “The city’s anemic red-light district was festooned with red, white and blue bunting; several of the smut peddlers featured dancers in elephant costume in their windows.”

Reagan’s Revolution (2005)

Page 322: “About the only person in Kansas City who was keeping cool was Reagan himself . . . Reagan, watching on television, dissolved in laughter.”

The Invisible Bridge (2014)

Page 785: “Just about the only person who was calm through the entire thing was Ronald Reagan. He watched it on television in his hotel suite, dissolving in laughter.”

S&S spokesman Cary Goldstein said to the New York Post, “We have examined Mr. Shirley’s claims, found them to be entirely without merit, and responded to him accordingly.” He continued, “In ‘The Invisible Bridge,’ Rick Perlstein, an acclaimed and award-winning historian and author, has written an 800-plus page masterwork that draws upon hundreds of sources, all of which are amply credited in more than 4,000 citations.”